Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States

There are specific structures that can be observed in bone fragments, which allows for the determination as to whether they might have come from a dinosaur. One such determining factor is the location where the bone was found. Initially, this sample was found in the Morrison Formation in Colorado, where dinosaur remains are common.
The estimated age of this region, and the geologic formations there, corresponds to the middle part of the dinosaur period—the Jurassic period. The most confirming element of the analysis of these samples is that a dinosaur bone itself is five or six times thicker than the largest adult male human long bone. That being shared,
this sample had to have come from a very large animal. Contrary to its appearance, the red structure within the quartz-filled medullary cavity is not a nutrient artery.
Soft tissue rarely becomes fossilized, and when it does, it is rarely replaced by quartz. The red color comes principally from hematite, an iron oxide. In the lower right of this photomicrograph is the metaphyseal bone, also called spongy bone, with blue chalcedony visible between the spicules.